1. Field of the Invention
The present invention relates to a puddle type developing apparatus, and a developing method using the apparatus.
2. Description of the Prior Art
In order to form a circuit on a surface of a substrate to be treated such as a semiconductor wafer, a photoresist is applied to the surface of the substrate, a circuit pattern is transferred to the photoresist by using photolithography technology, and a developing solution is supplied to a surface on which an undeveloped image pattern is formed, whereby a developed image pattern is formed on the surface of the substrate by developing the applied resist film.
There are several types of development such as a type in which a substrate to be treated is immersed in a developing solution, a type in which a developing solution is caused to flow as a shower on a surface of a substrate to be treated, or a puddle type in which a developing solution is applied over a photoresist on a surface of a substrate to be treated and the developing solution is thrown off by rotating the substrate to be treated after a lapse of a predetermined period of time. The types other than the puddle type have a drawback that a large amount of developing solution needs to be used.
Document 1 and Document 2 have disclosed a puddle type developing means. Document 1 has disclosed that a developing solution is applied over a surface of a substrate by using a slit nozzle, and thereafter the developing solution is withdrawn by using another nozzle so as to regenerate and reuse the withdrawn developing solution. Document 2 has disclosed that a developing solution is applied over a surface of a substrate, and thereafter the developing solution is withdrawn by covering the substrate with a case to which a sucking nozzle is connected, so as to regenerate and reuse the withdrawn developing solution.
[Document 1] Japanese Patent Application Publication No. 8-45832
[Document 2] Japanese Patent Application Publication No. 10-12540
In a common puddle type, a developing solution is replaced four to five times for conducting developing treatment to a single wafer. Development is conducted a plurality of times continuously. If a new solution is used for each development, a great volume of developing solution will be required. Therefore, by withdrawing and regenerating the used developing solution as disclosed in Documents 1 and 2, it is possible to make good use of the developing solution. However, in order to regenerate the used solution, it is necessary to conduct a regenerating treatment of the used solution by using a regenerating apparatus.
The present inventors have made this invention by paying attention to the fact that even a used solution has enough developing ability if the concentration of the solution is high.